In recent years, progress has been made in developing a transparent display that not only displays an image in accordance with image signals supplied from an external device but also allows the background to be seen therethrough. The transparent display has been gradually put on the market. As an example of such a transparent display, PTL 1 discloses a liquid crystal display device in which a prism is arranged between a liquid crystal panel and a light guide plate and a direction of light emitted from the light guide plate is changed by the prism to the normal direction of the light guide plate.